Simulate
Command ElementPerforms a single simulation.
Format
<Simulate
analysis_type = "string"
[ start_time = "real" ]
[ end_time = "real" ]
[ duration = "real" ]
[ restart_array_id = "integer" ]
[{
num_step = "integer"
print_increment = "integer"
print_interval = "real"
print_array_id = "integer"
}]
/>Attributes
- analysis_type
- Specifies the analysis that is to be performed. Options include:
- "Static"
- "Transient"
- "Linear"
- "Assembly"
- start_time
- Defines the starting value of the independent variable, Time.
- This attribute is optional.
- Defaults to 0.0 when not specified.
- end_time
- Defines the end time of the simulation.
- duration
- Defines the duration of the simulation. Use this when you do not know the end_time of your simulation beforehand.
- restart_array_id
- Specifies the ID of the Reference_Array element that contains
the time steps at which the integrator is to be restarted. Restarting the
integrator results in the integrator history being discarded.
- This attribute is optional.
- This is particularly useful when the model configuration has changed.
- num_steps
- Defines the number of output steps to take between start_time and
end_time.
- This attribute is optional.
- When specified, num_steps > 0.
- print_increment
- Specifies the frequency of output in terms of the integrator steps that have been taken. An
output is performed when the function MOD
(integration_step_number,
print_increment) = 0.
- This attribute is optional.
- When specified, print_increment > 0
- print_increment = 1 generates outputs at every integration step.
- print_increment = n generates outputs at every nth integration step.
- print_interval
- Defines the time interval between consecutive output steps for plotting and animation output.
- This attribute is optional
- Defaults to 0.01 when not specified
- When specified, print_interval > 0
Note: The maximum integrator step size (Param_Transient::h_max) is set to the print_interval if the print_interval is smaller than h_max. - print_array_id (optional)
- Defines the ID of the Reference_Array element that contains the time steps at which the output is desired.
Example
The example below demonstrates a Simulate command being used to perform a static equilibrium.
<Simulate
analysis_type = "static"
/>The three examples below demonstrate a Simulate command being used to perform a quasi static simulation. They are all equivalent.
<Simulate
analysis_type = "static"
end_time = "9.76"
num_steps = "976"
/>
<Simulate
analysis_type = "static"
end_time = "9.76"
print_interval = "0.01"
/>
<Simulate
analysis_type = "static"
start_time = "0.0"
end_time = "9.76"
print_interval = "0.01"
/>The example below demonstrates the use of print_array_id to generate unequally spaced outputs. For this simulation, output is generated at Time = 0.0, 0.1, 0.21, 0.33, 0.46, 0.60, 0.75, 0.91, 0.935, 0.95 and 1.0.
<Simulate
analysis_type = "static"
end_time = "1.0"
print_array_id = "21"
/>
<Reference_Array
id = "21"
type = "PRINT"
num_element = "11" >
0.0000000E+00 0.1000000E+00 0.2100000E+00 0.3300000E+00 0.4600000E+00
0.6000000E+00 0.7500000E+00 0.9100000E+02 0.9350000E+02 0.9500000E+00
1.0000000E+00
</Reference_Array>The example below shows the Simulate command being used for a typical transient simulation.
<Simulate
analysis_type = "transient"
end_time = "2.0"
num_steps = "1024"
/>The example below shows the Simulate command being used in conjunction with the restart_array_id to perform a simulation, but perform restarts at the mentioned times. The integrator is requested to perform a restart at Time = 0.16, 0.25, 0.43, 0.67 and 1.46 seconds.
<Simulate
analysis_type = "transient"
end_time = "2.0"
restart_array_id = "17"
/>
<Reference_Array
id = "17"
type = "RESTART"
num_element = "5" >
0.1600000E+00 0.2500000E+00 0.4300000E+00 0.6700000E+00 1.4600000E+00
</Reference_Array>The example below demonstrates two equivalent ways to perform a static analysis followed by a dynamic analysis.
<Simulate <Simulate
analysis_type = "static" analysis_type = "static"
/> />
<Simulate <Simulate
analysis_type = "transient" analysis_type = "transient
end_time = "1.5" end_time = "1.5"
num_steps = "150" print_increment = "100"
/> />The example below demonstrates a Simulate command being used to perform an assembly analysis.
<Simulate
analysis_type = "assembly"
/>Comments
- MotionSolve allows you to perform several different analyses in a single run. Different Simulate commands may be interspersed with other commands to modify the model or reset the simulation parameters and perform subsequent analyses. This provides a very powerful capability to perform complex simulations.
- For systems that have a static equilibrium position, it is always a good idea to perform a static analysis followed by a dynamic or transient analysis. The static analysis equilibrates the system and removes unbalanced forces. The dynamic analysis, consequentially, does not have much initial transience and simulations can be much faster.
- Complex simulation scenarios may be authored in the user-written subroutine, CONSUB. MotionSolve provides a complete API for interrogating the model, obtaining the current state of the model and performing analysis. CONSUB may be authored in a scripting language such as Python or in a programming language such as C++/C or Fortran.
- For controlling the output frequency, you may use
print_increment, num_steps,
print_array_id or print_interval. If the
model contains more than one of these attributes, the following precedence rules will
be honored by the solver:
Decreasing order of precedence:
print_increment > num_steps > print_array_id > print_interval